DATA SEGMENT
R DB ?
RES DB 10 DUP ('$')
MSG1 DB "ENTER RADIUS : $"
MSG2 DB 10,13,"VOLUME : $"
DATA ENDS
CODE SEGMENT
ASSUME DS:DATA,CS:CODE
START:
MOV AX,DATA
MOV DS,AX
LEA DX,MSG1
MOV AH,9
INT 21H
MOV AH,1
INT 21H
SUB AL,30H
MOV R,AL
MOV AH,0
MUL R
MUL R
MOV DL,88
MUL DL
MOV DX,0
MOV BX,21
DIV BX
LEA SI,RES
CALL HEX2DEC
LEA DX,MSG2
MOV AH,9
INT 21H
LEA DX,RES
MOV AH,9
INT 21H
MOV AH,4CH
INT 21H
CODE ENDS
HEX2DEC PROC NEAR
MOV CX,0
MOV BX,10
LOOP1: MOV DX,0
DIV BX
ADD DL,30H
PUSH DX
INC CX
CMP AX,9
JG LOOP1
ADD AL,30H
MOV [SI],AL
LOOP2: POP AX
INC SI
MOV [SI],AL
LOOP LOOP2
RET
HEX2DEC ENDP
END START
Explanation :
In this Assembly Language Programming, A single program is divided
into four Segments which are 1. Data Segment, 2. Code Segment, 3. Stack
Segment, and 4. Extra Segment. Now, from these one is compulsory i.e.
Code Segment if at all you don’t need variable(s) for your program.if
you need variable(s) for your program you will need two Segments i.e.
Code Segment and Data Segment.
CODE SEGMENT
CODE SEGMENT is the starting point of the
Code Segment in a Program and CODE is the name given to this segment and
SEGMENT is the keyword for defining Segments, Where we can write the
coding of the program.
ASSUME DS:DATA CS:CODE
In this Assembly Language Programming, their are Different Registers
present for Different Purpose So we have to assume DATA is the name
given to Data Segment register and CODE is the name given to Code
Segment register (SS,ES are used in the same way as CS,DS )
START:
START is the label used to show the
starting point of the code which is written in the Code Segment. : is
used to define a label as in C programming.
MOV AX,DATA
MOV DS,AX
After Assuming DATA and CODE Segment, Still it is compulsory to
initialize Data Segment to DS register. MOV is a keyword to move the
second element into the first element. But we cannot move DATA Directly
to DS due to MOV commands restriction, Hence we move DATA to AX and then
from AX to DS. AX is the first and most important register in the ALU
unit. This part is also called INITIALIZATION OF DATA SEGMENT and It is
important so that the Data elements or variables in the DATA Segment are
made accessable. Other Segments are not needed to be initialized, Only
assuming is enhalf.
Next Line – LEA DX,MSG1
MOV AH,9
INT 21H
The above three line code is used to print String or Message present
in the character Array till $ symbol which tells the compiler to stop.
Now, lets understand line by line
LEA DX,MSG1 in this LEA stands for LOAD EFFECTIVE ADDRESS and it
loads the effective address of second element into the first element.
This same code can be interchangably written as MOV DX, OFFSET
MSG1 where OFFSET means effective address and MOV means move second
element into the first element.
MOV AH,9
INT 21H
The above two line code is used to PRINT the String or Message of the address present in DX register.
Standard Input and Standard Output related Interupts are found in INT
21H which is also called as DOS interrupt. It works with the value of
AH register, If the Value is 9 or 9h, That means PRINT the String or
Message of the address present in DX register.
MOV AH,1
INT 21H
The above three line code is used to Read a Character from Console and save the value entered in variable R in its ASCII form.
Standard Input and Standard Output related Interupts are found in INT
21H which is also called as DOS interrupt. It works with the value of
AH register, If the Value is 1 or 1h, That means READ a Character from
Console, Echo it on screen and save the value entered in AL register.
SUB AL,30H
MOV R,AL
MOV AH,0
The above Two line code is used to convert the value entered in
variable R from ASCII form to its BCD form. This can be done
by subtracting 30H i.e. SUB AL,30H. The value
coming from Console is Basically in ASCII form. eg. When you enter 5 we
see 35H,So by subtracting 30H we get back to value as 5. SUB AL,30H means subtracting 30H from AL. MOV R,AL means move value in AL register into variable R. MOV AH,0 is used to clear the unwanted value (garbage value) in AH register is removed by assigning ZERO to it.
MUL R
MUL R
The above line code is used to Multiply R i.e. Radius with the Radius present in AX register
MUL R in this line R variable will be Multiplied with AL register (BY DEFAULT). This will give R*R (R SQUARE). Now, again MUL R in this line R variable will be Multiplied with AL register (BY DEFAULT). This will give R*R*R (R CUDE).
Now, Let me tell you Formula of Volume of Sphere :- 4/3 pi r*r*r (
pi= 22/7 ) This can be written (4*22*r*r*r)/(3/7) future simplified
will give you (r*r*r*88)/21. <—-this is what we are IMPLIMENTING.
MOV DL,88
MUL DL
The above line code is used to Multiply AX register by 88 i.e. R*R*R (R CUDE) value present in AX register
MUL 88 cannot be used hence We first move 88 to DL register i.e. MOV DL,88. After that MUL DL
in this line DL register will be Multiplied with AX register (BY
DEFAULT) in which the resultant value of R*R*R (i.e. R CUDE) is present.
Now, This will give (R*R*R*88).
MOV DX,0
MOV DX,0 is used to clear the unwanted value (garbage value) in DX register is removed by assigning ZERO to it.
This is done for Dividing the Bigger Value inside the AX register and
the Divisor will not fit inside 8 bit register AL register. Hence we
have to use AX register to get the Divisor this can be done by Dividing
16 bit register. When we Divide 16 bit register AX:DX both registers
are considered for Division. Here AX register will hold Quoitent and DX
register will hold Remainder.
MOV BX,21
DIV BX
The above line code is used to Divide AX register by 21 i.e. (R*R*R*88) value present in AX register
DIV 21 cannot be used hence We first move 21 to BX register i.e. MOV BX,21. After that DIV BX
in this line value in BX register will Divide AX:DX register (BY
DEFAULT) in which the resultant value of (R*R*R*88) is present. Now,
This will give (R*R*R*88)/21.
LEA SI,RES
CALL HEX2DEC
The above Two line code is used to initialize RES to SI register and
Call Procedure HEX2DEC which will covert AX register value as result and
Print it on user screen.
LEA SI,RES is used to Load Effective Address of RES variable to SI Register.
CALL HEX2DEC is used to Call a Procedure named HEX2DEC
LEA DX,MSG2
MOV AH,9
INT 21H
The above two line code is used to PRINT the String or Message of the address present in DX register i.e. for MSG2.
LEA DX,RES
MOV AH,9
INT 21H
The above three line code is used to print String or Message present
in the character Array till $ symbol which tells the compiler to stop.
As we have initialized all the values in an Array to $ you will think
what will be printed. The procedure is going to change the Array to its
Resultant Decimal equivalent printable form i.e. ASCII form of a digit
number.
Now, lets understand line by line
LEA DX,RES in this LEA stands for LOAD
EFFECTIVE ADDRESS and it loads the effective address of second element
into the first element. This same code can be interchangably written as
MOV DX, OFFSET RES where OFFSET means effective address and MOV means move second element into the first element.
MOV AH,9
INT 21H
The above two line code is used to PRINT the String or Message of the address present in DX register.
Standard Input and Standard Output related Interupts are found in INT
21H which is also called as DOS interrupt. It works with the value of
AH register, If the Value is 9 or 9h, That means PRINT the String or
Message of the address present in DX register.
EXIT: MOV AH,4CH
INT 21H
The above two line code is used to exit to dos or exit to operating
system. Standard Input and Standard Output related Interupts are found
in INT 21H which is also called as DOS interrupt. It works with the
value of AH register, If the Value is 4ch, That means Return to
Operating System or DOS which is the End of the program.
CODE ENDS
CODE ENDS is the End point of the Code
Segment in a Program. We can write just ENDS But to differentiate the
end of which segment it is of which we have to write the same name given
to the Code Segment.
PROCEDURE Code starts here:
Procedure is a part of code that can be called from a program in order to perform specific task.
HEX2DEC PROC NEAR
This line of code is used to start a procedure code and we can make
out the procedure by the keyword PROC which tells us the procedure is
started. In assembly language we have two types of Procedures one is
NEAR and other is FAR. NEAR is used to call the Procedure within the
program whereas FAR is used to call the procedure outside
the program. HEX2DEC is only the Name given to the Procedure Code.
MOV CX,0
MOV BX,10
MOV CX,0 is used to move or assign value 0
(decimal value) to CX. The program which we are wishing to write is
to covert HexaDecimal value to Decimal value, In which we will divide
the number till the Quotient is going to be Zero. CX register ( CX is
also Called COUNTER). CX register will count the number digit generated
by dividing the Hexadecimal number by Base value of Decimal i.e.Ten. MOV BX,10 in this Base value 10 is moved to BX register, So that it is used to divide hexa number by 10.
LOOP1: MOV DX,0
LOOP1: is a LABEL and all the words ending in colon (:) are Labels.
MOV DX,0 is used to clear the unwanted value (garbage value) in DX
register is removed by assigning ZERO to it. First Loop starts here.
DIV BX
ADD DL,30H
DIV instruction only works with REG or MEMORY hence we cannot use
DIV 10 where 10 is immediate, So we have to move 10 to BX register (we
can take any register) this we have already done above and Then DIV BX
Now DIV BX will Divide AX register with 10 which is passed to BX
register and Result of division is present in AX register contains
Quotientand DX register contains Remainder. Here we will not touch
Quotient AX as it will be used for furture Division, But DX Remainder
will be Decimal Digit and will always be less than Ten so the value will
be in DL register only and to make it printable on Console (Screen) we
have to add 30H So that it will become a ASCII character and will be
saved in Charater Array and will be printed as String later So ADD DL,30H.
PUSH DX
INC CX
PUSH is a stack function. Stack is an area of memory for keeping
temporary data. PUSH and POP are two stack operations which stores or
gets 16 bits of data. PUSH DX stores 16 bit data inside DX register into Stack Area. INC is a instruction for Increment the present in Register or Memory. INC CX will
increment the value present in CX register by One. Here we are using CX
register as a counter and counting the numbers of digits in their ASCII
form which are pushed into Stack. So that the same count will help to
POP the values out of Stack.
MOV CX,10
MOV CX,10 is used to move or assign value
10 (decimal value) to CX. The program which we are wishing to write is
to input ten characters from console which will be entered by the
user, Hence to do so we need a loop construct. In assembly
programming language we have a LOOP instruction. This works with two
other helpers which are Label and Counter. The Loop start with LABEL and
ends with LOOP instruction with the same LABEL name with it. the
execution of the Loop depends on the value in CX register ( CX is also
Called COUNTER).
CMP AX,9
JG LOOP1
CMP AX,9 is used to compare AX register
with 9 and jump if AX is greater to the respective LABEL LOOP1. The
result of Comparision is not stored anywhere, but flags are set
according to result. is Short Jump if first
operand is Greater then second operand (as set by CMP instruction).
Signed. SECOND is the label where the compiler will JUMP. First Loop ends here. Note :- this loop is without LOOP keyword and depends upon the number to be converted.
ADD AL,30H
MOV [SI],AL
ADD AL,30H The Last Remainder will
be Decimal Digit in AX register only as the number cannot be divided
future and will always be less than Ten so the value will be in AL
register only and to make it printable on Console (Screen) we have to
add 30H So that it will become a ASCII character and will be saved in
Charater Array and will be printed as String later. MOV [SI],AL Saving
the Characters in Character Array (i.e. String) is done by Moving AL
register to Address of SI register which is represented in Square
Brackets i.e. [SI]. SI is assigned with the Character Array i.e. RES.
LOOP2: POP AX
INC SI
LOOP2: is a LABEL and all the words ending
in colon (:) are Labels. POP is a stack function. Stack is an area of
memory for keeping temporary data. PUSH and POP are two stack operations
which stores or gets 16 bits of data. POP AX gets 16 bit data to AX register from Top of Stack. INC CX will
increment the value present in CX register by One. Here we are using CX
register as a counter and counting the numbers of digits in their ASCII
form which are pushed into Stack. So that the same count will help to
POP the values out of Stack and save it in AX register. Second Loop starts here.
MOV [SI],AL
The values out of Stack saved in AX register saved in string in this Loop. MOV [SI],AL Saving
the Characters in Character Array (i.e. String) is done by Moving AL
register to Address of SI register which is represented in Square
Brackets i.e. [SI]. SI is assigned with the Character Array i.e. RES.
LOOP LOOP2
This end of loop. In assembly programming language we have a
LOOP instruction. This works with two other helpers which are Label and
Counter. The Loop start with LABEL and ends with LOOP instruction with
the same LABEL name with it. the execution of the Loop depends on the
value in CX register ( CX is also Called COUNTER).
RET
RET is a
return instruction. This instruction is used only if the control is
been passed to the code outside Main like to Procedure. this return the
control to the place where the Procudure was called.
HEX2DEC ENDP
HEX2DEC ENDP is the End point of the Procedure in a Program.
This line of code is used to end the procedure code and we can make
out the procedure by the keyword ENDP which tells us the procedure is
ended. In assembly language we have two types of Procedures one is NEAR
and other is FAR. NEAR is used to call the Procedure within the program
whereas FAR is used to call the procedure outside the program. HEX2DEC
is only the Name given to the Procedure Code.
END START
END START is the end of the label used to show the ending point of the code whichis written in the Code Segment.
